High production rates of quality glassware articles such as glass containers, require that thermal energy be removed rapidly from the soft glass while it is blown or press formed against a mold.
For effecting very high rates of convective cooling, a fluid (usually air) is injected inside the glass.
Enhancement of this cooling mode was found when the cooling air inlet flow was introduced on the periphery of a hollow article with tangential flow causing a swirl current which afterwards is exhausted coaxially up from the center of said swirl current, as claimed and described in the U.S. Pat. No. 4,566,405.
Limited heat transference can also be effected by internally cooling the mold and therefore the outer wall of the glass.
This is achieved by providing a plurality of axial passages in the body of the mold or mold halves and introducing an air flow through said passages, from the botton to the top thereof, as described in U.S. Pat. Nos. 1,875,202; 3,355,277; 4,251,253 and 4,502,879.
In some of those cooling systems the molds keeps gradually accummulating heat because generally those cooling systems perform the cooling action only when the molds are closed but not when they are opened.
Furthermore the air flow within the passages is laminar and does not allows an effective heat extraction from the mold, because a rather static layer or film of hot air is formed along the internal wall of the passages.
Said rather static film of hot air in the walls of the passages is avoided and an improved heat transference is achieved in accordance with the present invention by providing a plurality of axial cooling passages having two opened ends, in the body of the molds or mold halves and a plurality of blowing heads each of which comprising an internal flow convertor and a central suctioning passage and is coupled to the top end of said cooling passages, in order to provide a continuous tangential flow of cooling air causing a swirl current downstream through the passages which is acelerated by a current of air that is suctioned through the central suctioning passage of the blowing heads and which afterwards is continuously exhausted through the bottom end of said cooling passages, efficiently cooling the molds and consequently the articles which are being formed, even when said molds or mold halves be in its opened state.